The invention relates generally to detecting diseases of the prostate, and more particularly, relates to reagents such as polynucleotide sequences and the polypeptide sequences encoded thereby, as well as methods which utilize these sequences, which are useful for detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining predisposition to diseases or conditions of the prostate such as prostate cancer. One polypeptide of the present invention is a serine protease.
Prostate cancer is the most common form of cancer occurring in males in the United States, with projections of 334,500 new cases diagnosed and 41,800 related deaths predicted to occur during 1997 (American Cancer Society). Prostate cancer also has shown the largest increase in incidence as compared to other types of cancer, increasing 142% from 1992 to 1996.
Procedures used for detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining predisposition to diseases or conditions of the prostate such as prostate cancer are of critical importance to the outcome of the patient. For example, patients diagnosed with localized prostate cancer have greater than a 90% five-year survival rate compared to a rate of 25 to 31% for patients diagnosed with distant metastasis. (American Cancer Society statistics). A diagnostic procedure for early detection of prostate cancer should, therefore, specifically detect this disease and be capable of detecting the presence of prostate cancer before symptoms appear.
Such procedures could include assays based upon the appearance of various disease markers in test samples such as blood, plasma, serum, or urine obtained by minimally invasive procedures which are detectable by immunological methods. These procedures would provide information to aid the physician in managing the patient with disease of the prostate and at low cost to the patient. Markers such as the prostate specific antigen (PSA) exist and are used clinically for screening patients for prostate cancer. Elevated levels of PSA protein in serum can be used as a marker in the early detection of prostate cancer in asymptomatic men. G. E. Hanks, et al., In: Cancer: Principles and Practice of Oncology, Vol. 1, Fourth Edition, pp. 1073-1113, Philadelphia, Pa. J.B. Lippincott Co. (1993.). PSA normally is secreted by the prostate at high levels into the seminal fluid, but is present in very low levels in the blood of men with normal prostates. However, in patients with diseases of the prostate including benign prostatic hyperplasia (BPH) and adenocarcinoma of the prostate, the level of PSA can be markedly elevated in the blood and thus be useful as an indicator of prostate disease. PSA, however, cannot differentiate between BPH and prostate cancer, which reduces its specificity as a marker for prostate cancer. M. K. Schwartz, et al., In: Cancer: Principles and Practice of Oncology, Vol. 1, Fourth Edition, pp. 531-542, Philadelphia, Pa. J.B. Lippincott Co. 1993. New markers which are more specific for prostate cancer thus would be beneficial in the initial detection of this disease.
A critical step in managing patients with prostate cancer is the presurgical staging of the cancer to provide prognostic value and criteria for designing optimal therapy. Improved procedures for accurately staging prostate cancer prior to surgery are needed. One study demonstrated that current methods of staging prostate cancer prior to surgery were incorrect approximately fifty percent (50%) of the time. F. Labrie, et al., Urology 44 (Symposium Issue): 29-37 (1994). Prostate cancer management also could be improved by utilizing new markers found in an inappropriate body compartment. Such markers could be MRNA or protein markers expressed by cells originating from the primary prostate tumor but residing in blood, bone marrow or lymph nodes and could be sensitive indicators for metastasis to these distal organs. For example, in patients with metastatic prostate cancer, PSA protein has been detected by immunohistochemical techniques in bone marrow, and PSA mRNA has been detected by RT-PCR in cells of blood, lymph nodes and bone marrow. K. Pantel, et al., Onkologie 18: 394-401 (1995).
New markers which could predict the biologic behavior of early prostate cancers would also be of significant value. Early prostate cancers that threaten or will threaten the life of the patient are more clinically important than those that do not or will not be a threat. G. E. Hanks, supra. A need therefore exists for new markers which can differentiate between the clinically important and unimportant prostate cancers. Such markers would allow the clinician to accurately identify and effectively treat early cancers localized to the prostate which could otherwise metastasize and kill the patient. Further, if one could show that such a marker characteristic of aggressive cancer was absent, the patient could be spared expensive and non-beneficial treatment.
It also would be beneficial to find a prostate associated marker which is more sensitive in detecting recurrence of prostate cancer than PSA and which is not affected by androgens. To date, PSA has proven to be the most sensitive marker for detecting recurrent disease. However, in some cases tumor progression occurs without PSA elevation due to hormonal therapy utilized for treating the cancer. Although the decrease in androgen results in a concomitant decrease in PSA, it does not necessarily reflect a decrease in tumor metastasis. This complication is the result of androgen-stimulated PSA expression. Part of the decline in PSA observed after androgen ablation is due not to tumor cell death but to diminished PSA expression. G. E. Hanks, supra.
PSA is a member of the human kallikrein gene family which is a family of serine proteases. A serine protease is a class of protein whose function is to accelerate proteolysis of a substrate protein. Proteolytic processes are thought to be the critical point in tumor invasion and metastasis, and are performed mainly by matrix metalloproteinases (MMPs) and serine proteases or proteinases. In some cases, apoptosis, or programmed cell death, may be prevented by serine protease inhibitors. Suzuki et al., Exp. Cell Res. 233 (1):48-55 (1997).
It therefore would be advantageous to provide specific methods and reagents for detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining predisposition to diseases and conditions of the prostate, or to indicate possible predisposition to these conditions. Such methods would include assaying a test sample for products of a gene which are overexpressed in prostate diseases and conditions such as cancer. Such methods may also include assaying a test sample for products of a gene alteration associated with prostate disease or condition. Such methods may further include assaying a test sample for products of a gene whose distribution among the various tissues and compartments of the body have been altered by a prostate-associated disease or condition such as cancer. Useful reagents include polynucleotides, or fragments thereof, which may be used in diagnostic methods such as reverse transcriptase-polymerase chain reaction (RT-PCR), PCR, or hybridization assays of mRNA extracted from biopsied tissue, blood or other test samples. Other useful reagents include polypeptides or proteins which are the translation products of such mRNAs, and antibodies directed against these polypeptides or proteins. Drug treatment or gene therapy for diseases or conditions of the prostate can then be based on these identified gene sequences or their expressed proteins and efficacy of any particular therapy can be monitored. Furthermore, it would be advantageous to have available alternative, non-surgical diagnostic methods capable of detecting early stage prostate disease such as cancer.